I tried doing no water changes on my tank to see if I could get it to work and after about 4 months I my tank seemed to be doing good and my corals were growing but slowly i thought so I felt with the nitrates being high at 50 I wanted to try going back to normal water changes but when I started doing it my tank got worse even a month into doing it weekly so I stoped again and my tanks looking better again but the nitrates have gone back up. Why is this and what should I do ?